Decoder, encoder and method for informed loudness estimation employing by-pass audio object signals in object-based audio coding systems

An encoder, comprising:

• an object-based encoding unit for encoding a plurality of audio object signals to acquire an encoded audio signal comprising the plurality of audio object signals, and
• an object loudness encoding unit for encoding loudness information on the audio object signals,
• wherein the loudness information comprises one or more loudness values, wherein each of the one or more loudness values depends on one or more of the audio object signals,
• wherein the object-based encoding unit is configured to receive the audio object signals, wherein each of the audio object signals is assigned to exactly one of two or more groups, wherein each of the two or more groups comprises one or more of the audio object signals,
• wherein the object-based encoding unit is configured to downmix the audio object signals, being comprised by the two or more groups, to acquire a downmix signal comprising one or more downmix audio channels as the encoded audio signal, wherein the number of the one or more downmix channels is smaller than the number of the audio object signals being comprised by the two or more groups,
• wherein the object loudness encoding unit is assigned to receive one or more further by-pass audio object signals, wherein each of the one or more further by-pass audio object signals is assigned to a third group, wherein each of the one or more further by-pass audio object signals is not comprised by the first group and is not comprised by the second group, wherein the object-based encoding unit is configured to not downmix the one or more further by-pass audio object signals within the downmix signal, and
• wherein the object loudness encoding unit is configured to determine a first loudness value, a second loudness value and a third loudness value of the loudness information, the first loudness value indicating a total loudness of the one or more audio object signals of the first group, the second loudness value indicating a total loudness of the one or more audio object signals of the second group, and the third loudness value indicating a total loudness of the one or more further by-pass audio object signals of the third group, or is configured to determine a first loudness value and a second loudness value of the loudness information, the first loudness value indicating a total loudness of the one or more audio object signals of the first group, and the second loudness value indicating a total loudness of the one or more audio object signals of the second group and of the one or more further by-pass audio object signals of the third group.

A method for generating an audio output signal comprising one or more audio output channels, wherein the method comprises:

• receiving an audio input signal comprising a plurality of audio object signals,
• receiving loudness information indicating information on the loudness of the audio object signals which are mixed within the downmix signal and indicating information on the loudness of the one or more further by-pass audio object signals which are not mixed within the downmix signal, and
• receiving rendering information indicating whether one or more of the audio object signals shall be amplified or attenuated,
• receiving a downmix signal comprising one or more downmix channels as the audio input signal, wherein the one or more downmix channels comprise the audio object signals, and wherein the number of the one or more downmix channels is smaller than the number of the audio object signals,
• receiving downmix information indicating how the audio object signals are mixed within the one or more downmix channels,
• receiving one or more further by-pass audio object signals, wherein the one or more further by-pass audio object signals are not mixed within the downmix signal,
• determining a loudness compensation value depending on the information on the loudness of the audio object signals which are mixed within the downmix signal, and depending on the information on the loudness of the one or more further by-pass audio object signals which are not mixed within the downmix signal, and
• generating the one or more audio output channels of the audio output signal from the audio input signal depending on the downmix information, depending on the rendering information and depending on the loudness compensation value.

A method for encoding, comprising:

• encoding an audio input signal comprising a plurality of audio object signals, and
• encoding loudness information on the audio object signals, wherein the loudness information comprises one or more loudness values, wherein each of the one or more loudness values depends on one or more of the audio object signals,
• wherein each of the audio object signals is assigned to exactly one of two or more groups, wherein each of the two or more groups comprises one or more of the audio object signals,
• wherein encoding the loudness information on the audio object signals is conducted by downmixing the audio object signals, being comprised by the two or more groups, to acquire a downmix signal comprising one or more downmix audio channels as the encoded audio signal, wherein the number of the one or more downmix channels is smaller than the number of the audio object signals being comprised by the two or more groups,
• wherein each of one or more further by-pass audio object signals is assigned to a third group, wherein each of the one or more further by-pass audio object signals is not comprised by the first group and is not comprised by the second group,
• wherein encoding the loudness information on the audio object signals is conducted by not downmixing the one or more further by-pass audio object signals within the downmix signal, and
• wherein encoding the loudness information on the audio object signals is conducted by determining a first loudness value, a second loudness value and a third loudness value of the loudness information, the first loudness value indicating a total loudness of the one or more audio object signals of the first group, the second loudness value indicating a total loudness of the one or more audio object signals of the second group, and the third loudness value indicating a total loudness of the one or more further by-pass audio object signals of the third group, or is configured to determine a first loudness value and a second loudness value of the loudness information, the first loudness value indicating a total loudness of the one or more audio object signals of the first group, and the second loudness value indicating a total loudness of the one or more audio object signals of the second group and of the one or more further by-pass audio object signals of the third group.